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This Study presents a numerical investigation of the hydro-thermal behavior of a Non-Newtonian ferrofluid (non-Newtonian base fluid and 4% Vol. Fe3O4) in a rectangular vertical duct in the presence of different magnetic fields, using two-phase mixture model, power-law model, and control volume technique. Considering the electrical conductivity of the base fluid, in addition to the ferrohydrodynamics principles, the magnetohydrodynamics principles have also been taken into account. To study the effects of non-Newtonian base fluid using power-law model, assuming the same flow consistency index with viscosity of Newtonian fluid, two different power law indexes (i.e., n=0.8 and 0.6), have been investigated and the results have been compared with that of Newtonian ones (i.e., n=1). Three cases for magnetic field have been considered to study mixed convection of the ferrofluid: non-uniform axial field, uniform transverse field and another case when both fields are applied simultaneously. The results indicate that the overall influence of magnetic fields on Nusselt number and friction factor is similar to the Newtonian case, although, by decreasing the power law index, the effect of axial field on velocity profile, Nusselt number and friction factor become more significant. Moreover, the results indicate that electrical conductivity has a significant effect on the behavior of ferrofluid and cannot be neglected and also negative gradient axial field and uniform transverse field act similarly and enhance both the Nusselt number and the friction factor, while positive gradient axial field decreases them.

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This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% ) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire parallelly located close to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field has been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes to produce kelvin force perpendicular to the ferrofluid flow changing axial velocity profile and creating a pair of vortices leads to increase the Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrate that the optimum value of magnetic number for Re_ff=50 is between Mn=1.33*10^6 and Mn=2.37*10^6 So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger.

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In this paper, drug coated magnetic nanoparticle delivery is numerically studied. Specific part of right foot vessel connected to the abdominal aorta is considered as target tissue. Single wire is applied as magnetic source. Buongiorno’s two-phase model is modified by adding the magnetophoresis term to the volume fraction transport equation. Governing unsteady equations with ferrohydrodynamics Kelvin force as a source term is discretized with PISO based finite volume method. Effects of the location of magnetic source and magnitude of current carrying from wire (1000, 2000, 3000, 4000 and 5000 amperes) are investigated on residence time and deposition level of drug on target tissue. Diameter and volume fraction of nanoparticles are 10 nm and 0.002, respectively. From the results, location of wire should be near and upstream the target tissue. Furthermore, by using this method deposition level of drug on target tissue can be increased by 7.5 times. Best drug delivery performance is seen for current magnitude of 2000 amperes.

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Nowadays, magnetic nanofluids have drawn a lot of attention toward themselves due to various applications in different fields such as medicine and industry. In this paper, for the first time new pumping method for magnetic nanofluids and ferro-fluids is presented. Moreover, magnetic nanofluid flow inside a rectangular channel under the effect of nonuniform magnetic field of permanent magnet is investigated. Iron oxide nanoparticles which lie completely homogeneous inside the based fluid of water are used. The governing equations obtained by adding the Kelvin body force term to the Navier-Stokes equations, and the equations are discretized using finite volume method and PISO algorithm. In order to study the effective parameters in the function of the FHD micro pump, a selected ranges of nanoparticles size, volume fraction of nanoparticles, saturated magnetization, and the length and width of the magnet are studied. The results demonstrate the increase in any of the mentioned parameters leads to rise in velocity magnitude inside the channel. Change in the diameter of magnetic nanoparticles has greatest effect on the velocity magnitude inside the channel. Furthermore, vertical magnet has better performance than horizontal one in FHD micro pump.